Shared Genetic Risk in the Association of Screen Time With Psychiatric Problems in Children

This cohort study evaluates the extent of genetic confounding in the association of screen time with mental health problems among preadolescent children.

use, divided by weekdays and weekends.The questionnaire asks how many hours per weekday/weekend day the child uses different types of screen-based media, with responses ranging from "0 h" (0) to "4 + h" (4).The STQ assesses screen time use for six different forms of recreational media use: television shows and movies, videos, video games, texting, social media, and video chat.The total amount of time spent on screens on an individual weekday or weekend day is a composite across all six forms of media types.In sensitivity analysis and for comparison, we also used a shorter parent-report STQ.This shorter version assesses only the child's total screen time on weekdays and weekend days in hours without specified subtypes of screen time.
Daily screen time averaged across both weekdays and weekends was used in our analysis.In our analysis, we standardized both child-rated and parent-rated screen time to mean 0 and standard deviation (SD) 1 for better comparisons.

Covariates
Family income and parental education were considered as additional potential confounders in the associations between screen time and child psychiatric problems.Family annual income was categorized into 10 levels, from less than $5000 to more than $200,000.
Parental education was evaluated as a categorical variable ranging from 0 representing 'never attended school' to 21 representing a doctoral degree (the highest attainment).We also additionally included maternal psychopathology as potential confounder to examine potential bias from using the parental informants for exposure and outcome, i.e., parents, on both child screen time and psychiatric problems.Meanwhile, Maternal psychopathology was included as a covariate to reduce the bias from using a parental informant for exposure and outcome.Maternal psychopathology was evaluated with continuous sum scores from the Adult Self Report questionnaire. 1

Heritability
The heritability estimates of child-reported (or parent-reported) child screen time, attention problem raw scores, and internalizing problem raw scores were estimated using the largest available sample of unrelated individuals from ABCD study with European ancestry.
Screen time and psychiatric domain scores were normalized prior to deriving the heritability estimates to fulfill the normal distribution assumption using GREML.
To conduct the identiy by descent (IBD) segments, we used the cut-off proportion of loci with 0 allele shared by descent (Z0) less than 0.1 and proportion of loci with 1 allele shared by descent (Z1) less than 0.1 to identify monozygotic twins and the cut-off of Z0 larger than 0.125 or Z0 less than 0.375 to identify dizygotic twins.eFigure 5. Association of child screen time (self-reported) with attention problems and internalizing problems: with different adjustments for genetic confounding using genetic information on the outcome (GsensY) (N=4262).
A. Attention problems

B. Internalizing problems
Model 1: adjusted for polygenic risk scores for outcomes only.Model 2: adjusted for polygenic risk scores using SNP-based heritability (h SNP ) for outcomes.Model 3: adjusted for polygenic risk scores using twin-based heritability (h twin ) for outcomes.eFigure 6. Association of child screen time (self-reported) with attention problems and internalizing problems: with different adjustments for genetic confounding and additionally residualizing on socioeconomic status (SES) (N=4262).
A. Attention problems B Model 1: adjusted for polygenic risk scores for both exposure and outcomes only.Model 2: adjusted for polygenic risk scores using SNP-based heritability (h SNP ) for both exposure and outcomes.Model 3: adjusted for polygenic risk scores using twin-based heritability (h twin ) for both exposure and outcomes.
eFigure 7. Association of parent-rated child screen time with attention problems and internalizing problems: with different adjustments for genetic confounding (N=4262).
A. Attention problems

B. Internalizing problems
Model 1: adjusted for polygenic risk scores for both exposure and outcomes only.Model 2: adjusted for polygenic risk scores using SNP-based heritability (h SNP ) for both exposure and outcomes.Note: Because we could not obtain a reliable twin-based heritability estimate for parent-rated screen time, model 3 is not included in our analysis here. eReference PRSs were all standardized to mean 0 and standard deviation 1 © 2023 Zhang Y et al.JAMA Network Open eFigure 4. Association of child watching television or video time and playing video game time with attention problems and internalizing problems: with different adjustments for genetic confounding (N=4262).

eFigure 8 .
Sensitivity analyses of genetic confounding using different SNP-based heritability simulated values of ADHD in two scenarios of screen time heritabilities.A. Attention problemsNote: Television time in adults was used as the phenotype in the reference of screen time heritability estimates (h2=0.16,green line).Clinically diagnosed ADHD cases and controls were used in the reference of attention heritability (showed as squares, h2=0.216).The triangle showed the observed h2 of attention problems (0.15) in our study sample and the circles showed the simulated possible h2 estimates of attention problems.B.Internalizing problemsThe Moods and Feelings Questionnaire (MFQ) reported by parents at 12-year-old was used as the phenotype in the reference (showed as squares, h2=0.017).The triangle showed the observed h2 of internalizing problems (0.036) in our study sample and the circles showed the simulated possible h2 estimates of internalizing problems.
4. Heritability estimates of screen subtypes and corresponding sample sizes in our study.Comparison of associations between child-rated versus parent-rated reported screen time and psychiatric symptoms (N=4262).Model 1 adjusted for sex and age.Model 2 adjusted for sex, age, family income, parental education.Associations of polygenic scores with child-reported screen time, attention and internalizing problems (supplemented with eFigure 2).
Note: PRS were adjusted for sex and top 10 PC, CBCL scores were additionally adjusted for sex, age and site, and screen time was additionally adjusted for sex, age, site.The estimated correlation in the parentheses used screen time residualzed on sex, age, site, family income and parental education.All variables were standardized to mean 0 and standardized deviation 1. eFigure 1. Original and transformed distribution of child reported screen time, parent reported child attention and internalizing problems.© 2023 Zhang Y et al.JAMA Network Open eTable 2. Demographic distribution of European unrelated individuals.a Parent-reported screen time questionnaire was less detailed than the child reported one, only asking for overall screen time in average.© 2023 Zhang Y et al.JAMA Network Open eTable 3. Demographic distributions of European children with genetic data compared with European children without genetic data.P-values were calculated with t-test for continuous variables and z-test for categorical variables.eTable eFigure 3. Comparison of associations between polygenic scores (PRS) and child-rated versus parent-rated screen time (N=4262).Associations adjusted for age, sex, site, and top 10 PCs.Noted: Polygenic risk scores, child-rated screen time and parent-rated screen time were standardized to mean 0 and standardized deviation 1. © 2023 Zhang Y et al.JAMA Network Open eTable 6.
© 2023 Zhang Y et al.JAMA Network Open eTable 7. Association of screen time with attention and internalizing problems: with different adjustments for genetic confounding, additionally adjusting for socioeconomic status.